JPH07234030A - Method and apparatus for refrigerating and liquefying by cold thermal storage type refrigerator - Google Patents

Abstract

PURPOSE:To provide a method and an apparatus for refrigerating and liquefying at a cryogenic temperature with an excellent efficiency. CONSTITUTION:This method for refrigerating and liquefying by a cold thermal storage type refrigerator comprises the steps of introducing an operating fluid of the ambient temperature discharged from a first displacer 12 to a second displacer 10, and generating a temperature lower than a temperature generated in an expansion space of the displacer 12 in its expansion space, wherein number of revolutions of the displacer 10 is set to 1/5 1/2 of that of the displacer 12.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention uses a regenerator having a regenerator having two regenerators or a displacer as a main element to cool liquid nitrogen at a temperature of 78 K or less and a superfluid temperature of helium.
The present invention relates to a refrigeration liquefaction method and device using a high-efficiency cold-storage refrigerator, which is characterized in that a temperature in a K region is generated to liquefy or freeze a gas.

[0002]

[Background Art] Conventionally, a cold storage type refrigeration system having a regenerator as a main element includes a Solvay, Taconis, and Gifford-McMahon (hereinafter referred to as GM) cycle. This is a system using a so-called cold storage type refrigerator that forms a refrigeration cycle using a vessel.In the Solvay cycle, an expander for adiabatic expansion is used, and in the Gifford-McMahon cycle, a displacer for moving a fluid to perform isothermal expansion is used. . It is called a displacer including an expander and a displacer.

FIG. 4 shows a typical flow path system of a GM refrigerator, in which a high-pressure working fluid (gas such as helium or the like, hereinafter referred to as fluid) 102 at room temperature from a compressor 101 is a pipe 103.
When the suction valve 104 is opened through a gas purifier (not shown), the displacer (including an expander of another refrigeration cycle) 130 that reciprocates in the cylinder 103 enters the room temperature space 105 from the bottom dead center. When it reaches the top dead center, the high-pressure fluid in the room temperature space 105 becomes displacer 130.
Are contained in the expansion spaces 126 and 128 while being cooled by the regenerator 105 made of a material such as a metal mesh, a lead ball, and a rare earth, which has a relatively large specific heat per volume in a low temperature region. When the suction valve 4 is closed and the displacer further moves to the top dead center, the discharge valve 104 opens and the expansion space 12
The high-pressure fluids 6 and 128 work to adiabatically expand the fluid in the low-pressure pipes to low temperature, low pressure, cool the regenerator 105, reach normal temperature, and return to the suction port 135 of the compressor. And one cycle ends.
By continuously performing this, the cold head 108,
At 125, refrigeration at each temperature is obtained.

Disadvantages of this refrigerator are, for example, that a reciprocating displacer is rotated at 120 rpm and a temperature at 108 is 77 K using a compressor of 4 KW consuming power.
If the refrigeration amount is 50 W, the refrigerating amount of 20 K and 5 W can be easily obtained with 125, but if the temperature of 125 is lowered to 8 K, the refrigerating amount is drastically reduced to about 1 W. The same applies to the frozen amount at 108. As a countermeasure against this, the expansion space 12
It can be improved to some extent by changing the volume of 8,126 or its volume ratio, but there is a limit. In the experiment, the required temperature of the expansion spaces 128, 126 (cold head 10
It has become clear that optimum operating conditions exist according to the same meaning as 8, 125).

That is, when the required freezing / liquefying temperature is 50 K to 120 K in the expansion space 128, the operating pressure is 10 atm or more, the expansion pressure ratio in the displacer is increased, and the faster the rotation speed is, the higher the freezing is. The output is large, and the efficiency (refrigeration output / consumed power = coefficient of performance) is also improved, but the durability of the displacer deteriorates.

[0006]

DISCLOSURE OF THE INVENTION The present invention proposes a method and apparatus that sufficiently solves this deficiency by an inexpensive method. That is, in the expansion space 126, when a refrigeration temperature of about 8 K is required, an operating pressure of 1 which is the reverse of the operating condition of 128 described above.
20 to 60r lower than 120 rpm at 0 atm or less
Experiments have shown that a low rpm of pm is sufficient. That is, theoretically, the specific heat and specific gravity of helium suddenly increase and the heat capacity of the regenerator material of the regenerator is insufficient, and the theoretical sound velocity of helium decreases as the temperature decreases, and the specific gravity increases. It is clear that when the velocity of helium is high, the pressure loss increases, the temperature does not drop, the refrigeration amount cannot be sufficiently obtained, and the efficiency decreases.

Particularly, the pressure loss at a low temperature is large, and for example, the length from the room temperature to the low temperature portion of the displacer is 50 cm in order to reduce the solid heat inflow through the wall of the displacer and the cylinder when the low temperature is set to 8K.
You need some degree. However, when the fluid passes through the gap between the metal or odd-earth regenerator made of mesh, powder, spheres, etc. contained therein, the actual length at the time becomes approximately several times the displacer length. When operated at 120 rpm, valves 4 and 10 open and close twice each second,
The helium gas that reciprocates between the room temperature and the expansion space 128 via the regenerator has an actual flow path length of 5 mm in the displacer.
If you double

At 2 * 2 * 50 * 5 = 1000 cm / s, it becomes 10 m / s.
That is, the sound velocity is 300K at 1024m / s at 10 atmospheres, but becomes 274m / s at 20K. At 8K, it will be 193m / s. When the displacer is operated at 120 rpm, its speed is 10 m / s, which is about 1/20 of the speed of sound. In the experiment, the displacer is 1Hz
It was found that if the operation is performed below, that is, the gas velocity is set to 5 m / s or less, a lower temperature is obtained and the efficiency is increased. It is known from the calculation that the pressure loss also becomes 1/4 when the gas velocity is halved, and these can be easily understood.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an embodiment of the present invention and is a flow path diagram of a refrigerator constituted by combining two expanders or displacers. The compressor 1 has a high pressure (for example, 15 to 21 atm). The working fluid (mainly helium, hereinafter referred to as a fluid) 2 passes through a radiator 3 and a purifier (not shown), is connected to a connecting rod 14 of the first displacer 12, and corresponds to the volume of the expansion space 13. By opening the first valve 4 (while the second valve 15 is closed during this period), the first cold accumulator 5 is gradually cooled by 6 and the first cold head 8 by 7.
(Cooling the cryopump and other radiation shields 60-12
(0K), by precooling the relatively long second regenerator 21 of the second system and the cylinder 11 of the second displacer 10 by the second cold head 9, the temperature rises slightly and enters the first expansion space 13.

At this time, the first valve 4 is closed, the first displacer 12 rises and expands to the top dead center, and the temperature further drops. At this time, the second valve 15 is opened and the displacer 12 moves toward the bottom dead center, so that the fluid in the expansion space 13 is pushed out and passes through each of the parts 9, 8, 7, 5, 6, 15 and reaches the room temperature to reach the first temperature. It enters into the buffer tank 18 and the purifier 19 which also serves as a filter. This completes one cycle of low temperature generation by the first system displacer. The first valve 4 and the second valve 15
Is opened and closed by a crank portion 16 with a motor 17 that is connected to the connecting rod 14 of the first displacer 12 and is driven according to the volume of the expansion space 13.

Next, this fluid having a medium pressure (for example, 8 to
(10 atm) is gradually cooled by the second regenerator 21 from the opening of the third valve 20 and from the second cold head 27 (cooling of the second radiation shielding plate and heat of the JT system) from 23. (Used for cooling the exchanger) to cool the first expansion space 28 of the second displacer 10 and a cooler 24 filled with a magnetic material having a large specific heat and a lead ball as a heat storage material to achieve a minimum temperature, The expansion space 26 enters from the third cold head 25. Since the third valve 20 is closed and the second displacer 10 is heading to the top dead center, the fluid is expanded and 4 to
It will be 6K. In the process in which the third valve 20 is closed, the fourth valve 29 is opened, and the second displacer 10 is moving toward the bottom dead center, the fluid in the expansion space 26 gives cold heat to the parts 25, 24, and 21 and is close to room temperature. Then, the flow returns from 22, 29, and 34 to the suction side 35 of the compressor 1 to complete one cycle of the second system.

The third valve 20 and the fourth valve 29 are opened and closed by the position of the second displacer 10 (the volume of the expansion space) of the motor 33, the crank portion 32, and the connecting rod 31, as in the first system. The low temperature generation is performed by continuously performing the displacer of the first system and the second system.

In the buffer tank 18 installed between the first system and the second system, the displacers 12 and 10 have different rotational speeds, and the pressure fluctuation of the fluid in each part of the second system is reduced to reduce the power loss. This is an essential element for the highly efficient refrigerating liquefaction apparatus of the present invention in order to reduce the amount. In general, a lower rotation speed of the second displacer 10 can generate a lower temperature. For example, in the generation of 4K, when the first displacer 12 is 120 rpm, the second displacer 10 is 30-60 rpm. In addition, the first system is operated mainly in the generation of the 60 to 120K region, and the rotation speed suction pressure can be adjusted independently of the second system according to the freezing temperature and the freezing output. The valve 37 is for adjusting the fluid leaking from the room temperature space 30 of the second displacer 10 between the connecting rods 31 and entering the second buffer tank 36, and is independent of 18.

FIG. 2 is a flow path diagram of another embodiment of the present invention with higher efficiency. The compressor is a two-stage compression type compressor (one-stage compressor, in which the intake of the first stage is 46, the discharge 45, the intermediate radiator 44, the second stage is 42, and the discharge is 2 at both ends of the shaft of the motor 43. Can be connected in series, but the efficiency of the motor is 2
This is an example in which (it goes down because it becomes a stand).

FIG. 5 shows an outline of the number of compression stages and power consumption. When the suction pressure, the discharge pressure, and the flow rate of the fluid are constant with the same fluid, theoretically and empirically, the unit flow rate increases as the number of compression stages increases. Power consumption per hit is reduced. Regardless of the type of compressor, such as piston type, scroll type, vane or other rotary piston type, the power consumption tends to decrease as the number of stages increases. In the present invention, in order to take full advantage of this feature, when a large refrigeration amount is required in the 60 to 120K region, the expansion pressure ratio of the first displacer 12 is increased to increase the flow rate.
The valve 39 is installed at 8 and the valve 40 is returned to the medium pressure tank 41. This facilitated adjustment of the refrigeration output in the 60 to 120K region.

FIG. 3 shows a large number of heat exchangers 48, 49 for continuously and efficiently producing temperatures up to 20 K and 2 K, and transferring refrigeration to a distant place to liquefy or freeze gas.
In this embodiment, 50, 51 and 52 and a Joule Thomson valve 53 are added. The high-pressure fluid from the compressor is branched at 47 to the first valve 4 of the first displacer and the heat exchanger 48, becomes low pressure by isenthalpic expansion at the Joule-Thomson valve 53, and the cold head 54 obtains the minimum temperature. Freezing and gas liquefaction are carried out. The valves 55 and 56 are pressure control valves, and the minimum pressure of the second displacer is 1.5 to 5.
This is because it may be driven at a pressure of 3.1 atm, so that the pressure is adjusted to 1.0 to 1.4 atm on the low-pressure suction side 46 of the compressor.

Although the driving motors 17 and 33 for the crank portions 16 and 32 in FIG. 1 are independent, a decelerator is attached to the crank portion 16 by one motor 17 and the cone rod 3 is used.
It is also possible to make one reciprocating motion.

[Brief description of drawings]

FIG. 1 is a channel diagram of an example of the present invention.

FIG. 2 is a flow path diagram of another embodiment of the present invention.

FIG. 3 is a diagram showing an embodiment of the present invention in the case of transferring refrigeration to a distant place to liquefy and freeze gas.

FIG. 4 is a flow path diagram of a conventional example.

FIG. 5 is a diagram showing the relationship between the number of compressor stages and power consumption.

Claims (9)

[Claims] 1. A refrigeration liquefaction method comprising a combination of two expanders or displacers (hereinafter referred to as "displacers") that operate at different rotation speeds N1 and N2, wherein a high pressure operation from a compressor is performed. The fluid is introduced through the first valve into the low temperature expansion space of the first displacer, which produces a relatively higher refrigeration temperature than the first regenerator, and is expanded to generate a low temperature to cool the cooling body. The working fluid, which has become intermediate pressure later, is again discharged from the first regenerator through the second valve to the first buffer tank or crankcase (hereinafter referred to as buffer tank), and the working fluid is directly or After passing through the second regenerator from the third valve through the purifier, it is led to the two low temperature expansion spaces of the second displacer that generate a lower temperature than the first displacer, and the expansion of the low temperature expansion space. Each low temperature is generated by After cooling the cooling body, the cooling body is returned to the second regenerator again, and further returned to the suction port of the compressor via the fourth valve. 2. The rotation speed N1 of the first displacer.
Is 60 to 240 r. p. m preferably 60 to 120
r. p. 2. The cold accumulator according to claim 1, characterized in that the rotation speed N2 of the second displacer is 1/5 to 1/2 times, preferably 1/3 to 1/2 times that of N1. Liquefaction method using a rotary refrigerator. 3. The number of compression stages of the compressor is two, and the working fluid discharged from the first buffer tank is introduced into an intermediate portion between the first and second stages of the compressor. Further, the working fluid discharged through the second regenerator is introduced into the one-stage suction port of the compressor, and the method for refrigerating and liquefying by a regenerator according to claim 1 or 2 is characterized. 4. The first valve, the second valve, the third valve and the fourth valve.
Each opening and closing operation of the valve causes the first displacer and the second displacer to operate.
4. The method for refrigerating and liquefying a regenerator according to any one of claims 1 to 3, characterized in that it operates in correlation with each reciprocating operation of the displacer. 5. A heat exchanger is attached to the refrigeration amount generated in the first displacer and the second displacer,
5. A liquefaction of neon, hydrogen, helium or the like or freezing in the temperature range of these by adding a large number of heat exchangers or Jul-Thomson valves. Or a refrigerating liquefaction method using the regenerator of claim 1. 6. A refrigeration liquefaction apparatus comprising a combination of two displacers operating at different rotation speeds N1 and N2, wherein the refrigeration liquefaction apparatus is provided with a radiator on its discharge side. A first valve, a second valve, and a third valve that are interlocked with the movements of the compressor, the first and second regenerators, the first and second displacers, and the first and second displacers. Valve and fourth valve, and first and second buffer tanks, the first and second dispersers each have a freezing and expansion space at a lower part thereof, and the first disperser has a freezing and expanding space. The freezing and expansion space is engaged and conducted by a pipe provided with a first regenerator and a cooling means, and the two freezing and expansion spaces provided under the second disperser are provided for the respective second regenerators. Engagement is conducted by a pipe provided with a cooling means on the secondary side,
The first buffer tank is engaged and conducted with the primary side of the first regenerator via the second valve and with the primary side of the second regenerator via the third valve. A refrigerating liquefaction device using a regenerator, wherein the primary side of the second regenerator and the suction port of the gas compressor are engaged and conducted by a pipe through a fourth valve. 7. A rotation speed N1 of the first displacer.
Is 60 to 240 r. p. m preferably 60 to 120
r. p. 7. The regenerator according to claim 6, wherein m is m and the rotation speed N2 of the second displacer is 1/5 to 1/2 times, preferably 1/3 to 1/2 times that of N1. Liquefaction device using a freezer. 8. The compressor has two compression stages, and the working fluid discharged from the first buffer tank is introduced into an intermediate portion between the first and second stages of the compressor. 8. The piping is arranged so that the working fluid discharged through the second regenerator is introduced into the one-stage suction port of the compressor. Liquefaction liquefier with a cold storage refrigerator. 9. The first valve, the second valve, the third valve and the fourth valve
9. The valve according to claim 6, wherein each opening / closing operation of the valve is set to operate in correlation with each reciprocating operation of the first displacer and the second displacer. A refrigerating liquefaction device using the cold storage refrigerator according to any one of 1.